This invention relates to an apparatus and method for extending the useful life of a laser, and more particularly relates to such an apparatus and method in which a laser is kept in continuous operation only during the time that a coded symbol is present in a target area for scanning.
Lasers are used in many different types of devices and systems. One example of such a system is a merchandise checkout system in which a laser is included in a bar code reader for reading data associated with merchandise items purchased by a customer. Data encoded by means of the bar code and read by the reader may include manufacturer data, merchandise data, etc.
One type of laser frequently used in a bar code reader is a laser diode. If a laser diode is maintained continuously in an "on" condition, its lifetime may be relatively short, compared to the remainder of the bar code scanner, and replacement will be necessary. A method is therefore needed to increase the laser diode's lifetime in the operation of a bar code scanner, or other device in which a laser diode may be used.
Prior developments aimed at preventing damage to laser diodes from causes such as excessive temperature are known. One such development is disclosed in U.S. patent application Ser. No. 445,225, filed Dec. 4, 1989, inventor Stephen J. Ames, for "Method and Apparatus for Preventing Damage to a Temperature-Sensitive Semiconductor Device", assigned to the assignee of the present application; now U.S. Pat. No. 5,073,838, issued Dec. 17, 1991.